Author Topic: How can this happen  (Read 1397 times)

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Offline G7PSKTopic starter

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How can this happen
« on: February 08, 2022, 08:43:06 am »
How can the display turn upside down due to wrong resistors in the LCD.

 

Offline gamalot

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Re: How can this happen
« Reply #1 on: February 08, 2022, 10:37:47 am »
Maybe it's just a bit in one of the registers in the LCD controller that wasn't initialized correctly.
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Offline timenutgoblin

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Re: How can this happen
« Reply #2 on: February 08, 2022, 10:49:33 am »
How can the display turn upside down due to wrong resistors in the LCD.

Looking at the YouTube thumbnail image, I would argue that the dial face has been rotated 180 degrees and not inverted (vertically flipped) as the YouTube video title suggests. If the dial face was inverted, the text would read backwards and not forwards.
 

Offline Ian.M

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Re: How can this happen
« Reply #3 on: February 08, 2022, 11:01:13 am »
'Inverted' has two possible meanings - positionally inverted or color inverted.   It wasn't clear which was the fault behind this recall, but end user photos ( https://www.core77.com/posts/111994/Hyundais-Strange-Cold-Weather-UI-Bug-Digital-Dashboard-Rotates-Flips-Display ) show it is in fact positionally inverted by rotation (or both horizontal and vertical 'flips').   

Coding and testing to stringent safety standards cost money, and the more variants of the code there are, the higher the cost, and also even for modules sharing identical hardware, the cost of production is increased, and there are much higher inventory costs stocking and distributing several variants of physically identical subassemblies.   Its therefore logical to assume that Hyundai decided to minimize the number of types of display subassembly required by determining the configuration to use from the dash panel its fitted in. 

A common way to do this without using a lot of pins is to use a potential divider in the external circuit to encode the configuration option as an analog value to be read by an ADC input.  If one attempts to encode too many different choices, the values are too close together and especially if the ADC and potential divider don't share a common reference voltage, thresholds can shift resulting in the option being incorrectly decoded.   Temperature extremes often cause MCU on-chip reference voltages to shift.
« Last Edit: February 08, 2022, 12:18:31 pm by Ian.M »
 

Offline timenutgoblin

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Re: How can this happen
« Reply #4 on: February 08, 2022, 11:31:55 am »
'Inverted' has two possible meanings - positionally inverted or color inverted.   It wasn't clear which was the fault behind this recall, but end user photos ( https://www.core77.com/posts/111994/Hyundais-Strange-Cold-Weather-UI-Bug-Digital-Dashboard-Rotates-Flips-Display ) show it is in fact positionally inverted by rotation (or both horizontal and vertical 'flips').

I did think to consider that the dial face was colour inverted, but then I would expect the high temperature range to be blue/cyan instead of red as shown in the YouTube thumbnail.
 


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